. >>> erin, thanks. breaking news tonight in the sandy hook massacre. a possible motive emerging. a terrifying explanation of why adam lanza chose the target he did. and there is this. a face in the crowd when president obama was speaking out against kids being gunned down in chicago. just hours later, her young life was forever changed. >> also tonight, we've all been there, a crowded flight, a crying baby. but no matter how bad it gets, would you ever, ever slap the baby? we're going to show you the man who allegedly did do that, and talk to the baby's parents. >>> well, we begin with breaking news right now. potential answer, an utterly chilling one to the question, why did serial killer adam lanza target the sandy hook elementary school in newtown, connecticut. why did he pick that school to assault? law enforcement sources telling cbs news, the answer may lie across the atlantic in norway. at a summer camp near ososlo, where a man man hunted down and killed 69 people, most of them teenagers. brevic, who began his rampage with a bombing in oslo, ultimately murdered 77 people.